Prolonged Antibacterial Activity Research Articles

Gentamicin release from biodegradable poly-l-lactide based composites for novel intramedullary nails

One of the major problems in orthopedic surgery is infection associated with implantation. The treatment is a very difficult and long-term process. A solution to this issue can be the use of implants which additionally constitute an antibiotic carrier preventing the development of an infection. Prototypes of biodegradable intramedullary nails made of three different composites with a poly(l-lactide) matrix were designed. The nails served as gentamicin sulfate (GS) carrier — an antibiotic commonly used in the treatment of osteomyelitis. The matrix was reinforced with carbon fibers (CF), alginate fibers (Alg) and magnesium alloy wires (Mg), as well as modified with bioactive particles of tricalcium phosphate (TCP) in various systems. In this way, novel, multi-phase and multifunctional degradable intramedullary nails were obtained. The tests demonstrated strong dependence between the type of the modifying phase introduced into the composite, and the rate of drug release. Introduction of gentamicin into the nail structure strengthened and prolonged antibacterial activity of the nails.

Preparation and evaluation of periodontal films based on polyelectrolyte complex formation

Local intra-pocket drug delivery devices can provide an effective concentration of the antimicrobial agent at the site of action with avoidance of undesirable side effects. This study explored the application of chitosan-alginate and chitosan-pectin polyelectrolyte complex (PEC) films as drug release regulators for tetracycline HCl (Tc) to treat periodontal pockets. Periodontal films with 1:1 Tc:PEC ratio were prepared using 1:1 chitosan (Ch) to sodium alginate (A) or 1:3 Ch to pectin (P). The scanning electron microscope showed acceptable film appearance and differential scanning calorimetry analysis confirmed complex formation. The in vitro release studies for both films showed a burst drug release, followed by prolonged release for 70 h. A prolonged antibacterial activity of both films against Staphylococcus aureus ATCC 6538 was observed over a period of 21 days. Aging studies indicated that the five months storage period in freezer did not significantly influence the drug release profile or the antibacterial activity of both films. Clinical evaluation showed a significant reduction in pocket depth (p < 0.0001) to their normal values (≤3 mm). PEC films could be exploited as a prolonged drug release devices for treatment of periodontal pockets.

Advanced dextran based nanogels for fighting Staphylococcus aureus infections by sustained zinc release.

The growth in numbers and severity of hospital acquired infections has increased the need to target bacteria locally and specifically. Consequently, smart drug-delivery systems are being developed for local bactericidal action. The approach takes the concept of nanogels in drug delivery of small molecules to the next level by enclosing them in a shell. Versatile polysaccharide nanogels were loaded with zinc ions as antibacterial agents in a miniemulsion process, in order to target methicillin resistant strains of Staphylococcus aureus (MRSA). The encapsulation of drugs in nanogels is limited by the crosslinking density of the gel and the size of the drug. The characterization of the nanogels with inductively coupled plasma optical emission spectroscopy (ICP-OES) revealed that zinc ions cannot be retained within without an additional 'shell' layer. The nanogels were surrounded by a dextran-polyurethane shell, which can retain substances by reduction of water penetration. A delayed zinc release compared to the nanogels was confirmed by ICP-OES. Bacterial tests revealed an antibacterial effect of the shell enhanced nanogels against S. aureus. The studied nanogel system shows potential in locally addressing bacterial infections. The platform is extremely versatile and can be tailored to application as dextran and Zn(NO3)2 can be replaced by other polysaccharides (e.g. hyaluronic acid) and antibacterial agents, respectively.

Antibiotic-loaded silica nanoparticle-collagen composite hydrogels with prolonged antimicrobial activity for wound infection prevention.

Silica-collagen type I nanocomposite hydrogels are evaluated as medicated dressings to prevent infection in chronic wounds. Two antibiotics, gentamicin and rifamycin, are encapsulated in a single step within plain silica nanoparticles. Their antimicrobial efficiency against Pseudomonas aeruginosa and Staphylococcus aureus is assessed. Gentamycin-loaded 500 nm particles can be immobilized at high silica dose in concentrated collagen hydrogels without modifying their fibrillar structure or impacting on their rheological behavior and increases their proteolytic stability. Gentamicin release from the nanocomposites is sustained over 7 days, offering an unparalleled prolonged antibacterial activity. Particle immobilization also decreases their cytotoxicity towards surface-seeded fibroblast cells. Rifamycin-loaded 100 nm particles significantly alter the collagen hydrogel structure at high silica doses. The thus-obtained nanocomposites show no antibacterial efficiency, due to strong adsorption of rifamycin on collagen fibers. The complex interplay of interactions between drugs, silica and collagen is a key factor regulating the properties of these composite hydrogels as antibiotic-delivering biological dressings and must be taken into account for future extension to other wound healing agents.

The Biological Performance of Calcium Hydroxide–loaded Microcapsules

IntroductionCalcium hydroxide (Ca[OH]2) microcapsules were synthesized for use in controlled release. The aim of this study was to evaluate the cytotoxicity, antibacterial properties, and influence on gene expression of bone-related markers of 2 different formulas of Ca(OH)2 microcapsules. MethodsTwo formulas of Ca(OH)2 microcapsules (A and B) were evaluated, and pure Ca(OH)2 powder was used as a positive control. The shell material of formula A was pure EC, and the PLA/EC blend of 1:1 was used as the shell material for formula B. The MG63 cells/Cell Counting Kit-8 (Dojindo, Kumamoto, Japan) were used to evaluate the cytotoxicity, and the colony-forming units of Enterococcus faecalis were monitored for the antibacterial effect. The relative messenger RNA expression of collagen I and osteocalcin was determined by real-time polymerase chain reaction. ResultsBoth formulas of the Ca(OH)2 microcapsules showed no cytotoxicity in MG63 cells; however, the Ca(OH)2 positive control did exhibit cytotoxicity. The antibacterial effect of the 2 microcapsule formulas lasted longer than the positive control, and formula A lasted longer than formula B. For both Ca(OH)2 microcapsule formulas, the relative messenger RNA expression of collagen I and osteocalcin was prolonged and up-regulated. The time effects of the influence on messenger RNA expression of collagen I and osteocalcin were different between the 2 microcapsule formulas. ConclusionsCa(OH)2 microcapsules had prolonged antibacterial activity and prolonged the up-regulation of bone-related markers with reduced cytotoxicity.

Dithiocarbamate chitosan as a potential polymeric matrix for controlled drug release

Objective: To develop a polymer matrix for controlled release of drugs, chitosan, a linear aminopolysaccharide, was chemically modified to dithiocarbamate chitosan (DTCC) to afford a matrix where metal–drug complexes could be attached and released in a controlled manner depending on the binding nature between the drugs and the metals.Materials and methods: DTCC was treated with metal-tetracycline (Tc) complexes to prepare DTCC–Ca(II)–Tc, DTCC–Mg(II)–Tc, DTCC–Cu(II)–Tc and DTCC–Zn(II)–Tc.Results: The binding amount of Tc was in the order of DTCC–Zn(II)–Tc ≈ DTCC–Mg(II)–Tc ≈ DTCC–Ca(II)–Tc > DTCC–Cu(II)–Tc. The biphasic binding profiles, where Tc binding increased initially and then decreased, were shown for DTCC–Cu(II)–Tc and DTCC–Zn(II)–Tc. In a flow method, Tc was released slowly from DTCC–metal–Tc complexes except for DTCC–Cu(II)–Tc compared with Tc release from DTCC–Tc. In parallel with the results of the release experiment, DTCC–metal–Tc complexes except for DTCC–Cu(II)–Tc presented a prolonged antibacterial activity in an antibacterial test. The antibacterial activity of DTCC–Ca(II)–, –Mg(II)– and –Zn(II)–Tc complexes lasted for 28–44 days, while free Tc and DTCC–Tc lasted for 7–12 days.Discussion and conclusion: Taken together, our data suggest that DTCC could be used for a polymeric matrix for controlled release of drugs such as Tc, which possess functional groups for ionic and/or coordinate bond with metals.

Antibacterial properties and bioactivity of HACC- and HACC-Zein-modified mesoporous bioactive glass scaffolds.

Infection and its complications are one of the greatest threats to the health of orthopedic patients. Mesoporous bioglass (MBG) scaffolds are characterized by well-ordered, three-dimensional, nanometer-sized mesoporous structures, which facilitate the adhesion of hydroxyapatite and the loading of drugs. MBG has been widely used as a new-generation biomaterial in bone tissue engineering. However, MBG is very brittle and lacks antibacterial activity. This limits its applications in the treatment of bone defects, especially large bone defects complicated by infection. In order to dispel these disadvantages, a novel hydroxypropyltrimethyl ammonium chloride chitosan (HACC) and a class of prolamine proteins found in maize, Zeins, were here used to modify the traditional MBG scaffolds. Two new types of scaffold, MBG-HACC scaffolds and MBG-HACC-Zein scaffolds, were made. Transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), and Barrett-Joyner-Halenda (BJH) were used to analyze the surface properties of these MBG scaffolds. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), mechanical experiments, and synchrotron radiation microcomputer tomography (SRμCT) were used to compare the features of the traditional and modified scaffolds and to analyze the mineralization of the scaffold after being soaked in simulated body fluid (SBF). Confocal laser scanning microscopy (CLSM) was used to compare the antibacterial properties and biocompatibility of the scaffolds at various points in time. The current study demonstrates that all these prepared MBG scaffolds possessed well-ordered, three-dimensional, nanometer-sized mesoporous structures and that HACC-Zein-modified MBG scaffolds are characterized by strong bioactivity and by effective, prolonged antibacterial activity. Finally, biocompatibility was demonstrated by studying the in vitro proliferation and viability of human mesenchymal stem cells (hMSCs).

Physical and Antimicrobial Properties of Peppermint Oil Nanoemulsions

The mixture of peppermint oil (PO) with medium-chain triacylglycerol was emulsified in water and stabilized with a food-grade biopolymer, modified starch, to form PO nanoemulsions. The effects of emulsifying conditions including homogenization pressure, the number of processing cycles, and oil loading on the mean diameters and viscosities of nanoemulsions were characterized by dynamic light scattering, optical microscopy, and rheological measurements. The formulated PO nanoemulsions with mean diameters normally <200 nm showed high stability over at least 30 days of storage time. Their antimicrobial properties related to those of PO have also been evaluated by two assays, the minimum inhibitory concentration (MIC) and time-kill dynamic processes, against two Gram-positive bacterial strains of Listeria monocytogenes Scott A and Staphylococcus aureus ATCC 25923. Compared with bulk PO, the PO nanoemulsions showed prolonged antibacterial activities. The results suggest that the nanoemulsion technology can provide novel applications of essential oils in extending the shelf life of aqueous food products.

Experimental Development of New Surgical Suturing Materials with Complex Biological Activities

New surgical suturing materials with complex biological activities (antibacterial and stimulating tissue regeneration) have been developed. In vitro studies demonstrated pronounced and prolonged (up to 10-12 days) antibacterial activity. Experiments on 108 male albino rats proved the positive effect of the materials on the wound process: shortening of the inflammation period, more rapid transformation of the granulation tissue, more rapid epithelialization of the wound and its pronounced contraction.

Treatment of demodicosis in dogs: 2011 clinical practice guidelines

These guidelines were written by an international group of specialists with the aim to provide veterinarians with current recommendations for the diagnosis and treatment of canine demodicosis. Published studies of the various treatment options were reviewed and summarized. Where evidence in form of published studies was not available, expert consensus formed the base of the recommendations. Demodicosis can usually be diagnosed by deep skin scrapings or trichograms; in rare cases a skin biopsy may be needed for diagnosis. Immune suppression due to endoparasitism or malnutrition in young dogs and endocrine diseases, neoplasia and chemotherapy in older dogs are considered predisposing factors and should be diagnosed and treated to optimize the therapeutic outcome. Dogs with disease severity requiring parasiticidal therapy should not be bred. Secondary bacterial skin infections frequently complicate the disease and require topical and/or systemic antimicrobial therapy. There is good evidence for the efficacy of weekly amitraz rinses and daily oral macrocyclic lactones such as milbemycin oxime, ivermectin and moxidectin for the treatment of canine demodicosis. Weekly application of topical moxidectin can be useful in dogs with milder forms of the disease. There is some evidence for the efficacy of weekly or twice weekly subcutaneous or oral doramectin. Systemic macrocyclic lactones may cause neurological adverse effects in sensitive dogs, thus a gradual increase to the final therapeutic dose may be prudent (particularly in herding breeds). Treatment should be monitored with monthly skin scrapings and extended beyond clinical and microscopic cure to minimize recurrences.

Preparation and evaluation of microcrystallized cellulose xanthate-metal-oxytetracycline complexes as antibacterial agents with prolonged antibacterial activity

Microcrystallized cellulose xanthate-metal-oxytetracycline complexes (MCX-metal-OTC) were prepared and evaluated as a controlled release system for the antibiotics. Microcrystallized cellulose (MC) was chemically modified to xanthated microcrystallized cellulose (MCX). One-bath method, where MCX was reacted with OTC-metal complexes, afforded greater amount of OTC bound to the polymeric matrix than did two-bath method, where MCX-metal complexes were treated with OTC. The OTC release from MCX-metal-OTC was greatly sustained compared with that from a mixture of MC/metal/OTC. Furthermore, MCX-metal-OTC manifested antibacterial activity, which lasted for 11-18 days. These results suggest that MCX-metal-OTC is a polymeric antibiotics with prolonged antibacterial activity.

Covalent coating of hydroxyapatite by keratin stabilizes gentamicin release

A novel hybrid hydroxyapatite (HAP) matrix, covalently coated with rarely applied, hardly degradable keratin and effectively modified by gentamicin immobilized in mixed-type mode (via interactions of diverse strength), was created. This hybrid showed a remarkably high drug immobilization yield and the most sustainable antibiotic release among all tested composites. It was also able to inhibit bacterial growth, both in surrounding liquid and on matrix surface, much longer (for at least 121 days of experiment) than analogous gelatin-modified and nonmodified matrices. Gentamicin-keratin-coated-HAP granules were nontoxic to human osteoblasts and enabled their proliferation with a rate similar as noncoated HAP. Presence of keratin on HAP granules seemed to slightly enhance the osteoblast proliferation. The results indicate that newly created HAP hybrid with covalently immobilized keratin and gentamicin--nontoxic and osteoblast-friendly--is a promising biomaterial of significantly prolonged antibacterial activity.

Evaluation of Cellulose Xanthate-Metal-Tetracycline Complexes as a Polymeric Antibacterial Agent with Prolonged Antibacterial Activity

Cellulose xanthate-metal-tetracycline complexes (MCX-metal-Tc) were prepared and evaluated as a controlled release system for the antibiotics. Microcrystallized cellulose was chemically modified to cellulose xanthate (MCX). The amount of metal bound to MCX was 0.36 mmol Cu(II)/g MCX and 0.26 mmol Zn(II)/g MCX. Tetracycline (Tc) bound to MCX-metal chelates was 0.08 mmol/g MCX-Cu(II) and 0.04 mmol/g MCX-Zn(II). The Tc release from MCX-metal-Tc was greatly sustained compared with that from a mixture of cellulose/metal/Tc. Furthermore, MCX-metal-Tc manifested antibacterial activity that lasted for 7–22 days. These results suggest that MCX-metal-Tc is a polymeric antibacterial agent with prolonged antibacterial activity.

Human serum activity of telithromycin, azithromycin and amoxicillin/clavulanate against common aerobic and anaerobic respiratory pathogens

Telithromycin is a new ketolide antimicrobial with a good in vitro activity against both aerobic and anaerobic respiratory pathogens. In this study, we evaluated the antibacterial activity over time of telithromycin (800 mg), azithromycin (500 mg), and amoxicillin/clavulanate (875/125 mg) in serum following single oral doses of these agents to 10 healthy subjects. Inhibitory and bactericidal titers were determined at 2, 6, 12, and 24 h after each dose and the median titer was used to determine antibacterial activity. Against two azithromycin-resistant strains of Streptococcus pneumoniae, both telithromycin (MIC = 0.25 and 0.5 μg/mL) and amoxicillin/clavulanate exhibited inhibitory and cidal activity for at least 6 h. All three antibiotics provided prolonged (≥12 h) inhibitory activity against strains of Hemophilus influenzae (telithromycin MIC = 4.0 μg/ml). Both telithromycin and amoxicillin/clavulanate exhibited rapid and prolonged inhibitory activity (≥12 h) against each of the anaerobes studied ( Finegoldia [Peptostreptococcus] magna Peptostreptococcus micros, Prevotella bivia, and Prevotella melaninogenica). Moreover, both agents provided bactericidal activity against both Prevotella species. In this ex vivo pharmacodynamic study, we found that telithromycin provided rapid and prolonged antibacterial activity in serum against macrolide-resistant strains of S. pneumoniae, beta-lactamase-positive and -negative strains of H. influenzae, and common respiratory anaerobic pathogens. These findings suggest that telithromycin could have clinical utility in the treatment of community-acquired mixed aerobic–anaerobic respiratory tract infections, including chronic sinusitis and aspiration pneumonia.

Asymmetric chitosan membranes prepared by dry/wet phase separation: a new type of wound dressing for controlled antibacterial release

An AgSD-incorporated chitosan membrane with sustained antimicrobial capability has been developed by a dry/wet phase separation method to overcome current limitations in silver sulfadiazine (AgSD) cream for treating acute burn wounds. The asymmetric chitosan membrane consists of a dense skin and sponge-like porous layer, which can fit the requirements (oxygen permeability, controlled water vapor evaporation and the drainage of wound exudates) for this membrane to be used as a wound dressing. AgSD cream is a traditionally-used antibacterial for the prevention of wound infection; however, it has raised concern of potential silver toxicity. The asymmetric chitosan membrane acts as a rate-controlling wound dressing to incorporate AgSD, and release sulfadiazine and silver ions in a sustained way. The release mechanism depends on the mass-transfer resistance for the release of sulfadiazine and silver ions from the dense and sponge-like porous layers, and the chemical resistance for the interaction of silver ions with chitosan polymeric chains, respectively. The bacteria-cultures ( Pseudomonas aeruginosa and Staphylococcus aureus) and cell-culture (3T3 fibroblasts) assay of the AgSD-incorporated asymmetric chitosan membrane showed prolonged antibacterial activity and decreased potential silver toxicity. The results in this study indicate that the new type of chitosan wound dressing incorporated with AgSD may be effective in the treatment of infected wounds.

Cotton Fabrics with Prolonged Antibacterial Activity: Formation and Properties of Cotton Xanthate-Al(III)-Tetracycline Complex

Cotton fabrics with prolonged antibacterial activity were prepared by coupling the tetracycline (Tc) to fabrics via chelate bonds in the presence of Al (III) ion. To enhance the binding capacity of cotton via chelation, cotton was chemically modified with carbon disulfide in alkaline media to form xanthate groups. The coupling method greatly affected the binding of Tc to cotton xanthate (CX). In a one-bath process, where CX was treated with Al(III)-Tc solution in one step, binding of Tc took place readily and effectively with about 90 mg Tc/g CX on the average. In the two-bath process, CX was reacted with the solution of Al(III) ion in the first step to produce CX-Al(III) complex, which was isolated and reacted with a solution of Tc in the second step. The amount of binding was much lower than that from the one-bath process. The resulting product, CX-Al(III)-Tc complex, had a bright-yellow color and maintained the textile nature of the fabric. Release of Tc from CX-Al(III)-Tc, which was carried out by batch and flow methods, was almost constant during the first 6 hours. Antibacterial activity of CX-Al(III)-Tc was tested against Bacillus subtilis and Escherichia coli and it showed prolonged activity in comparison with that of free Tc.

Formation, Properties, and Antimicrobial Activity of a Cotton Xanthate-Cu(II)-Metronidazole Complex

To develop cotton derivatives with prolonged antibacterial activity, cotton is derivatized to cotton xanthate (CX) and coupled with metronidazole (Mz) by means of chelate bonding in the presence of Cu(II) using one- and two-bath processes. The effects of coupling methods, concentration, [Mz]/[Cu(II)] ratio, and reaction time on the formation of CX-Cu(II)-Mz are investigated at 10°C. In the one-bath process where CX is treated with a solution of the Cu(II)-Mz complex, binding of Mz takes place readily and rapidly and increases with a higher [Mz]/[Cu(II)] ratio. In the two-bath process, binding of Mz is much lower than in one bath. Release of Mz from CX-Cu(II)-Mz prepared from the one-bath process is investigated by the flow method and takes place steadily during the first 3 hours. The extent of release reaches 65-99% in 20 hours, depending on the concentration of Cu(II) and Mz used to form CX-Cu(II)-Mz. Antibacterial activity of CX-Cu(II)-Mz is tested against G(+) S. aureus, B. subtilis, and G(-) E. coli., and lasts longer than that of free Mz.

Pharmacokinetics of aditoprim in goats using a radioassay

A simple, highly sensitive radioassay was developed for the activity of a newly discovered inhibitor of dihydrofolate reductase (DHFR), aditoprim. The procedure is based on the inhibition of binding of [3H]-methotrexate ([3H]MTX) with bacterial dihydrofolate reductase by the antifolate, aditoprim. The analytic sensitivity using this binding inhibition method was less than 5 ng in plasma. The procedure developed requires no extraction of the drug from the plasma. The variation of simultaneous duplicate determinations was 6.3 per cent, whereas the variability of plasma samples assayed on different days was less than 11 per cent. The assay developed was applied to study the pharmacokinetics of aditoprim in the goat. In comparison with trimethoprim (TMP), the new inhibitor of DHFR, aditoprim, had a longer half-life and a larger volume of distribution, suggesting enhanced and prolonged antibacterial activity of aditoprim over TMP.

Control of prosthetic bacterial infection: Evaluation of an easily incorporated, tightly bound, silver antibiotic PTFE graft

Despite the use of prophylactic antibiotics in vascular surgery, prosthetic infection rate remains 2–5%. Antibiotics bound to vascular prostheses can control experimentally induced infection but prolonged antibacterial activity has not been achieved. This study evaluates the in vivo efficacy and antibiotic retention of an easily prepared silver-antibiotic prosthesis. Prostheses were prepared by combining silver with oxacillin or amikacin using an organic solvent. After evaporation of the solvent, the graft was left impregnated with the antibiotic complex. In vivo retention studies were performed by implanting PTFE 110Ag-oxacillin prostheses in four canine abdominal aortas. When prostheses were explanted at 1 week, mean antibiotic retention was found to be 20% of original activity, higher than the mean inhibitory concentration for Staphylococcus aureus. In three groups of five dogs, 20 × 7-mm prostheses of PTFE alone, PTFE silver-oxacillin, or PTFE silver-amikacin were implanted in the abdominal aorta and the grafts were inoculated with 10 7 S. aureus of a known bacteriophage type, in a closed retroperitoneal pocket. The animals were sacrificed at 1 week and the prostheses were excised for quantitative bacterial culture. PFTE silver-oxacillin, and PTFE silver-amikacin prostheses had 1.7 × 10 2 and 2.0 × 10 2 colonies, respectively, significantly less ( P < 0.05) than controls (1.3 × 10 6 colonies). These data suggest that antibiotic prostheses can be easily prepared without binding agents. They retain the bound antibiotic for a prolonged period and are effective in reducing graft infection in a stringent direct contamination model.

PTFE graft treated with silver norfloxacin (AgNF): Drug retention and resistance to bacterial challenge

Norfloxacin (NF) and silver norfloxacin (AgNF) were used to coat polytetrafluoroethylene (PTFE) vascular prostheses by using triododecylmethylammonium chloride as a cationic surfactant. The relative retention of the drug on the graft after subjecting it to the biological environment for 3 weeks and antibacterial activity against coagulase-positive Staphylococcus aureus and Escherichia coli were determined. In addition, the ability of AgNF-coated PTFE grafts to sterilize perigraft tissue after mixed bacterial contamination was studied and compared with control PTFE grafts in 10 dogs. At the end of 21 days, 15 and 18% of AgNF were retained on the grafts tested in in vitro and in vivo experiments, respectively. During the same time AgNF-coated grafts from in vitro experiments exhibited significant antibacterial activity (25 mm zone of inhibition (z.i.)), but antibacterial activity was negligible (10 mm z.i.) in the grafts from in vivo experiments. NF retention on the grafts could not be determined because of spectral interference by blood. The antibacterial activity of NF-coated grafts significantly declined after 24 hr in in vivo experiments, hence further evaluation of NF-coated grafts was not done. Seven perigraft sites surrounding AgNF-coated grafts were sterile, but only one perigraft site surrounding control grafts was sterile ( P < 0.05). Cultures from six of nine perigraft infections surrounding control grafts yielded heavy bacterial growth. There was only one wound infection at the site of AgNF graft while there were seven severe wound infections at control graft sites. AgNF-coated grafts exhibited prolonged antibacterial activity compared to NF-coated grafts and offered significant protection against infection from local bacterial contamination.